Long-term objectives: This is a collaborative research effort between the laboratories of Dr. Cecilia Hillard, a basic scientist studying cannabinoid receptor function using animal and cellular models; and Dr. Harriet de Wit, a psychologist studying the effects of gender on stress responsivity and susceptibility to substance abuse in humans. One long term objective of this project is to solidify this collaborative relationship which will enhance both individual research projects through the addition of translational aims that bridge them. We will develop this collaboration through an Exploratory/Developmental project that will begin to test the hypothesis that gender differences in the effects of stress on endocannabinoid (eCB) signaling contribute to the gender differences in susceptibility to psychiatric disorders, including substance abuse. It is well established that depression and anxiety occur more frequently in women than in men, which suggests a gender difference in reactivity to stressful or threatening situations. Therefore, studies of gender differences in response to stress will clarify the differential vulnerability of women and men to these and other stress-related disorders, particularly substance abuse. The Specific Aims of the project are to determine the effects of gender and estrous stage in mice on: (1) the role of eCB/CB1 receptor signaling in the regulation of basal and stress-induced hypothalamic-pituitary-adrenal axis activation; and (2) expression of CB1 receptors, CB1 receptor function and the expression of eCB synthetic and catabolic proteins in brain regions known to be involved in the stress response. A second goal of this proposal is to explore the relationship between serum eCBs and gender differences in the human stress response. In particular, we will compare the responses to stress and serum eCBs in men and women in both the follicular and luteal phases. We will: (1) measure serum eCB contents in blood collected during two sessions: one that is a control visit to the research area, and the second during and after the administration of the Trier Social Stress Test; and (2) examine the relationships among serum eCB contents, gender/sex hormone status and indicators of the stress response, including ratings of anxiety, heart rate and salivary cortisol levels. These pilot studies will guide the development of hypothesis-driven translational research projects that will further explore the interactions among stress, gender, the risks of developing substance abuse and a novel and important signaling system in the brain, the endocannabinoids and their receptor, CB1. Stress is increasingly recognized as a significant risk factor for the development of many diseases in humans, including cardiovascular disease, depression, anxiety disorders and substance abuse disorders. Men and women differ in their responses to stressful life situations and differ in the stress-related diseases that they develop. Data collected in animals demonstrate that endocannabinoid signaling is "stress-protective". In addition, limited data suggest that endocannabinoid signaling differs between male and female rodents. The goal of the studies in this proposal are to expand the animal studies and to add human studies to determine whether gender differences in endocannabinoid signaling underlie or contribute to gender differences in stress responses. [unreadable] [unreadable] [unreadable] [unreadable]